1. Field of the Invention
The present invention relates to an epoxy resin composition.
2. Background Information
Adhesive strength and flexibility at low temperatures as well as at elevated temperatures are sometimes required of structural adhesives.
For example, methods combining spot-welding and adhesives (weld-bonding) have been adopted to provide body rigidity, strength, and other attributes to automotive vehicles in components such as roof rails and various pillars, and the adhesives employed in such weld-bonding preferably have high adhesive strength on steel sheets at elevated temperatures of about 80° C. This is because components such as roof rails and various pillars sometimes become very hot while the vehicle is travelling. This is also because the number of spots in spot welding can be reduced if the adhesive strength is high.
Also, for example, components referred to as openings (lidded), such as the hood, doors, and trunk lid, are basically constructed of outer plates (outer panels) and inner plates (inner panels), and a crimping structure referred to as a “hemming” is used along virtually the entire periphery of the ends, but the adhesive used to affix the hemming part will preferably have adhesive strength and flexibility at elevated temperature. This is because the hemming sometimes heats up to an elevated temperature of about 80° C. while the automotive vehicle is travelling. It is also because stress is not dispersed and tends to become concentrated at one point when a load is imposed on locations where the hemming is bonded.
An example related to such an adhesive is disclosed in Patent Document 1: JP-A 5-214310.
Patent Document 1 discloses a pseudo-curable epoxy resin adhesive composition characterized by comprising (A) a specific epoxy resin, (B) a core-shell powdered polymer with specific properties having a two-layered core/shell structure, and (C) a thermally activated curing agent as essential components. This type of composition is disclosed as being characterized by better adhesive performance, such as impact resistance and tensile shear strength or T-peel strength, and by good pseudo-curability and the like.